1. Field of the Invention
The present invention relates to a touch panel device and a touch positioning method thereof, and more particularly, to a touch panel device having high touch sensitivity and a touch positioning method thereof.
2. Description of the Prior Art
Along with the requirement of a friendly communication interface for a user to interact with an electronic device, a touch panel for controlling operations of the electronic device by directly touching the panel with fingers, instead of using a keyboard or a mouse, has gained popularity. In general, touch panels are primarily classified into the resistive touch panels and the capacitive touch panels. The resistive touch panel positions a touched position according to related voltage drops changing in response to the touched position. The capacitive touch panel normally comprises a plurality of sensing capacitors, and the touched position can be positioned by analyzing the changing of capacitance of the sensing capacitor corresponding to the touched position.
FIG. 1 is a structural diagram schematically showing a prior-art touch panel device 100. As shown in FIG. 1, the touch panel device 100 includes a touch panel 101, a plurality of sensing lines 110, a plurality of sensing capacitors 120, a plurality of storage capacitors 140, and a plurality of comparators 150. Each sensing capacitor 120 can be an equivalent capacitor of one corresponding sensing line 110. When the touch panel 101 is touched, the capacitance of a sensing capacitor 120 corresponding to touched position increases accordingly and, in turn, a power source Vdd will furnish more charges to a corresponding sensing line 110 for boosting the capacitor voltage of a corresponding storage capacitor 140. The capacitor voltage of the corresponding storage capacitor 140 is then compared with a reference voltage Vref by a corresponding comparator 150 for generating a touch readout signal. However, if the size of a touch panel is larger, the equivalent capacitance of each sensing line is greater, which results in a lower variation regarding the capacitor voltage of one storage capacitor corresponding to a touch event. That is, regarding a prior-art touch panel device, touch sensitivity is lower with larger touch panel size.